In the past, U.S. Pat. No. 2,099,944 described a process of treating bast fiber plants to obtain clean cellulose fiber, lignin, and other gums, comprised of the following steps: 1) warm air drying; 2) rapid temperature reduction; and, 3) prolonged exposure to chilled ionized air. Ozone naturally attacks the carbon bonds of the lignin and nitrous oxide helps remove the pectins and other gums.
The process described is similar to modern ozonolysis systems, which are designed for pretreatment of lignocellulosic materials in order to remove lignin and facilitate enzymatic digestion of the carbohydrates into biofuels. Modern ozonolysis systems expose lignocellulosic materials within a reaction chamber at room temperature and atmospheric pressure to gaseous ozone for a prolonged period of time.
Rapid depressurization to vacuum and repressurization to atmospheric pressure or greater within a vacuum chamber or any suitable pressure vessel has never been contemplated for the purpose of degumming bast fiber. Vacuum rapidly dries and opens the fibrous material. Vacuum also aids in the penetration and diffusion of ionized air within the fibrous material upon repressurization.
U.S. Pat. No. 5,207,870 contemplates the use of vacuum to pretreat wood chips, however the process does not employ rapid pressure swings and the wood chips are in chemical liquid solution not ionized air.
U.S. Pat. No. 5,344,462 discusses the treatment of cellulose, textile fibers, and polymer films by exposure to low pressure plasma discharge. This process does not contemplate rapid pressure swings and it is designed for surface modification of the treated materials, not degumming for textile applications or pretreatment for biofuels production.